Through his company, Murray, who has won three Grand Slam titles, manages athletes and fellow tennis players.
Porteous and Murray, both 19, played for Hibs’ first team last season as the club finished fourth in the Premiership.
“Ever since my grandad played for Hibs in the 1950s, my family have supported the club,” said Murray, 31.
“We were impressed with the quality of the facilities and the people working there. It feels like a natural and authentic partnership.
“Football is a huge passion of mine and I’m looking forward to working with the club - and with Ryan and Fraser and helping them with every aspect of their careers.
“Hibs have a great youth set-up and with the team of people I have around me, we’ll be helping them in any way we can.”
Murray’s grandfather Roy Erskine started his career at Easter Road and later played for Stirling Albion and Cowdenbeath.
77 Sports Management will work with existing coaches and staff at the Capital club’s academy.
Club chief executive Leeann Dempster said: “We are delighted to be working in partnership with a world-class sportsman like Andy and his team.
“It offers our young players a chance to learn and be inspired by an elite athlete who knows exactly what it takes to perform at the highest levels possible.
“It is another very exciting development for the club.”
Porteous is delighted to get on board with Murray.
He said: “I had a few chats with Andy and his team and it has been positive. It wasn’t a full out chat but through text. I’ve not spoken to him in person yet.
“What he’s doing for young talent through that agency is brilliant. When he comes back from that injury he’s still got his best years ahead of him.
“But what he’s doing for British sport — his agency isn’t just tennis, it’s athletics and football too — is unbelievable.
“It’s surreal. I am a sports fan in general and I’ve watched him growing up. I think every Scottish person has seen him as an inspiration.”